Class Insecta 537 



XVII CorrodeWtia f 



I Thysanura 



Annelid-like ancestor 



■• VII Ephemerida 



Fig. 177. — Representative insects. The lines suggest possible relationsliips. 

 The figures are not to scale. (From: Hegner and Stiles; College Zoology, 1951, 

 with permission from The Macmillan Company.) 



